Liquid-meter.



Envnv e. BAILEY, or nnwroiv mennanns, massacrwsn'rrs, ASSIGNOR TO 3mm 5METER COMPANY, A coaroanrron' or massacnusn'rrs.

LIQUID-METER.

The present invention relates to a liquid meter, and is embodied in ameter having a dam or obstruction provided with means for egress of theliquid therethrough, said means ings which show the quantity of liquidmay for egress consisting of an aperture or. apertures, so shaped andlocated in the obstruction that the rate of flow of liquid through orpast the obstruction will vary in any desired relation to the headproducing the flow.

The invention is particularly useful in providing a simple and accuratemeter, in which the rate of flow of liquid is directly proportional tothe head, so that the readbe readily averaged, or integrated, eitherdirectly, by means of a known type of integratingdevice, or from a chartrecord.

The rate of flow of liquid through apertures of standard form, such asrectangular, triangular, and trapezoidal weirs, also, the rate of flowthrough circular and other shaped orifices, follows certain general laws"which are well known to the profession of hydraulic engineering. Thesegeneral laws, such as,

, swea nd e= wat -upon actual calibration of any of such meansSpecification of Letters Patent.

' Patented Oct. 23, 1am.

Application filed August 18, 1913. Serial No. 785,2 25.

ducible standard shaped apertures such as those named above. All of thecalibrations based on such work, however, show that the actual rate offlow does not vary in direct proportion to the head; so that readings ofthe head, covering a period of time, cannot be averaged for calculatingthe average rate of flow, nor can the readings be integrated by means ofany of'the usual forms of inte grating devices.

The present invention involves the shape and arrangement of an. apertureor apertures which form the means of egress of the liquid; the shape andcharacter of the actual outlet being such that the rate of flow ofliquid will be in direct proportion to the head, or, if desired, willfollow any desired relation to the head that may be useful.

In accordance with my invention, therefore, I form the boundaries of themeans of egress, so that the said means of egress consist substantiallyof a combination of one or more orifices in horizontal planes with oneor more weir-notches in vertical or inclined planes, said orifices andnotches being separate or connected, but in all cases being of suchshapes and proportions that the actual plane is made such that thecoefficient of discharge is an important factor in accomplishingthedesired relation between the rate of flow and head. I

I amaware that weirs have been previously'designed with a view toobtaining a rate of flow which is in a predetermined desired ratio tothe head; but all of such weirs have openings which are wholly in avertical plane, and the desired relation between fiow and head, whethera simple or a complex ratio, has been obtained by curving the verticalboundaries of theopening. Such weirs may be made to measure accuratelyover a portion of their range; but, although the necessary curve can betheoretically plotted by mathematical formulm, a variation from theexpected ratio between head and flow is found to result from changes inthe coefficient of discharge at different heads.

In order to make the weir measure accurately, therefore, eventhroughoutthe range in which it is possible, changes in the curve must be madewith the aid of observations taken at difi'erent heads, Furthermore. af-

ioo

till

ter a weir of a certain capacity has been constructed, the same curvecannot be followed in. constructing other weirs of greater or lesscapacity.

ln accordance with my invention, on the contrary, I duly consider, whenconstructing my meter, the laws governing the coefficient of dischargethrough openings diiiering in. shape, size and position, as well asthegeneral laws relating to the flow of liquids; and by so doing am enabledto use apertures which are bounded by straight lines or arcs of circles,so that the apertures when made through walls having plane surfaces areeasily reproducible.

To bring about this result, I locate part of the aperture in one plane,and part in another plane, the apertures being so arranged that the partin one plane constitutes what J is technically known as an orifice,while the part in the other plane constitutes what is technically knownas a weir-notch. In order to avoid objectional descriptive matter intheclaims, I- desire to state that by the term orifice mean an openingwhich lies substantially in a horizontal plane and is therefore whollybelow the level of the sur" face of the liquid when any material amountoi? liquid is flowing and that by the term weir-notch I mean an openingwhich is in a plane at an angle to the horizontal and is only partiallyand variably submerged. when the meter is in operation.

In my meter, as in the meters of the prior art, the necessary shape andarea of the entire means of egress must be finally dctermined byexperimental calibration; but when the necessary shape and area of theorifice, relative to the shape and area of the weir has oncebeendctermined, the same relation will substantially hold good in metersof different capacities, so that uniformity is established which is ofgreat advantage in the practical manufacture of the instrii noents.Furthermore, the meter can be constructed so that the reading will besubstantially correct throughout the entire range.

Figure 1 is a perspective view of a meter embodying the invention; andFigs. 2 and 3 are similar views showing modifications.

Referring to F ig. 1, the dam or obstruction consists of the walls 1 ofa reservoir having an inlet pipe 2 hr the liquid to be n'icasured, andany suitable device for indicating the level of the liquid, such as afloat The means of egress in this construction consist of the vertical,rectangular weir 4 and the horizontal triangular orifice 5, the latterbeing the space between the walls 6 and 7, which extend from the weirinto the reservoir.

.lt is practically impossible to express the d sign and proportion ofthe different parts e of aperture mathematically for the ,esa

problem is not capable of a direct mathematical solution, owing largelyto the very limited research work that has been done upon orifices ofvarious shapes and sizes in horizontal plates at comparatively lowheads, and the lack of knowledge of the ex act mathematicallawsgoverning the coefiicient of discharge. The practical development ofthe problem must be carried out by actual experiment and the finaldesign accepted will depend upon the end sought. If a meter of thegeneral design of Fig. l is desired to have a rate of discharge thatvaries in direct proportion to the head, it must be constructed with anyselected angle be tween intersecting plates 6 and 7, a selected widthand height of weir opening 4; ahd an actual calibration made. If thecalibration curve deviates from a straight line, the angle of theorifice or the width of the weir should be changed and anothercalibration made. Considerable data from such actual calibrations havebeen secured, the following being a. set of eleven runs at diiierentheads for a meter of this design;

- Cubic feet per h or head, Q or cubic feet Coefficient of inches. persecond. ig g l'mch discharge.

0. 407 039 0958 X83 1. 009 1057 1057 354 2. 021 229 1133 432 2. 859 3241133 468 3. 985 443 1112 435 8.992 .443 1110 .484 4. 997 550 1101 4915.990 660 1102 496 6. 003 664 .1108 499 l 8. 000 .QlO 1137 .512 9.9971.180 .1180 .522

In this case the width of the weir notch 4:

was 3.99 inches and is termed E); the altitude or length of thetriangular orifice 5, (assuming the boundary transverse to the directionof flow to be the base of the trian= gle) was 8.95 inches and is termeda; the head, or height of the surface of the liquid above the lowestpoint of egress varied from 0.407 to 9.997 inches, and is termed it.

The thcmatical equation for the discharge of liquid through such anaperture can probably best be expressed by;

fice having an area, and through a rectangular weir of width 1), except0 is the coeliicient of discharge of the combination.-

The coeificient has been calculated from the data of the calibrationtests and it is noted that in this particular case it varies from .183'at the lowest head to .522 at the highest. If this coefficient wereconstant it would be absolutely impossible to even approach a simpleratio relation between head and rate of discharge, but the coefficientof discharge is not constant and it varies in such a manner that therate of discharge per unit head is substantially constant as shown bythe third column of the above data. From about 1% to 8 inch heads therate of discharge per inch head does not vary 2 per cent. from theaverage, and a meter which has this degree of accuracy over 80% of'itscapacity compares very favorably with the best of other types of metersnow in general use. It is also quite possible to change the relationbetween a and b and thereby approach the desired result even closer thanthis, for the given case is only one particular design that was,selected from preliminary calibration Work. At any rate it is quitecertain that the rate of discharge at the lower heads could be increasedwithout materially afl'ecting it at the higher heads by changing theorlfice part from a single pointed triangle to a two or multipointedopening and thereby give more edge or perimeter for the discharge. Forit is obvious that a star shaped orifice in a horizontal plate will havea higher coeificient of discharge at low heads than a circular orificeof the same area, while at higher heads the shape has little effect.

This same end may be accomplished in modifying the design shown in Fig.1, so that the orifice and weirdo not join into one aperture, but areseparated in a manner similar to that shown in Fig. 2; and numerousother modifications or designs could be worked out withoutdeparting fromthe present invention.

If the greatest accuracy is not necessary at the lowest heads a meter ofthe type shown in Fig. 1 will giye a rate of flow substantially indirect proportion to the .head when the altitude or length of thetriangle is about 2% times the base, and the-maximum capacity of themeter will be the rate of flow corres design or geometrical shape of theapertures, any desired relationibetween head and rate of flow may besecured between the necessarily connected.

opening onding to a head of substan-. .ti ally two tlmes the width ofthe weir.

It obvious that by varying the relation between these dimensions or byvarying the limits of the laws governing the flow through simpleorifices on the one hand and the V-notchon the other, and still notdepart from the use of circular, triangular, rectangular, trapezoidaland other easily made and accurately reproducible shaped apertures. Theadvantage gained through the use of such apertures over curved edgedweirs such as shown in Patents 1042097 to Englebright and 1067 191 toSimmance and Abady is obvious, for in these the shapes of the curves canonly be determined by actual calibration and prolongedexperimentationand then the shape of the curve is different fordifferent capacities; while I have found that with my present inventionthe same design holds good for a variety of capacities, it only beingnecessary to increase or di- .minish all dimensions proportionally.

found to be expedient, and the apertures forming the entire means ofegress are not In the construction shown in Fig. 2, for example, I haveshown the weir 40, as trapezoidal in shape, and lying in a plane whlchis inclined from the vertical. The orifice 50 in this meter is shown asa plurality of openings of different, shapes. In Fig. 3, a meter isshown in which the orifice 500 is triangular in shape, as in the metershown in Fig. l, the said orifice, however, consisting of an through ahorizontal wall forming part 0 the dam. The weir 4:00 in this meter isshown as partly trapezoidal, this form of meter being especially adaptedfor use when the desired measurement depends upon a rate of flow which.varies as some definite function of the head other than a simple ratio.I

From the foregoing description, it will be seen an, my invention iscapable of wide and varied modifications dependent partly upon theparticular use to which it is put; but in all cases the successfulembodiment of the invention consists of a meter in which the sizes,shapes and positions of the ape'rtures which constitute the means ofegress, are determined in accordance with the laws of hydraulics,including those relating to the coefficient of discharge. a

What I claim is:' i 1. In a liquid meter, an obstruction having as meansfor egress for the liquids, weir notch, the entire boundary of whichliesf plane, the said plume be- I minutely tz'm'zsvelxe-lc t0 the direc*4. fiovq 15 liqnfid; combined with an the boundaw of which lies Whollyin while a, plans being approx "he zimction of Low ans fur measun theuqiilci at the upstream 5161a "33,011.

W n f J u. 11, mg a non/Jamal x a 12m aitfimde times as inning a. Widthsubstantially equal to the bmev of said triangulm' apert'ure and a,

height appmxinmtely twice its Width; am? means for n'leasurmg the helghtof the 11culd the upstream SldQ of the obst mctl'onu. In testlmony'whereci, i. have slgncgdmy name to tins spcclficn'tlon 1n the presence ftwp subscnbmg wltnegses.

EQ IN G.

s JI BCLKLONEY 214. M. .L0NEY.

